In C, accessing my array index is faster or accessing by pointer is faster?

Question

In C, accessing an array index is faster or accessing by pointer is faster? By faster I mean, which one would take less clock cycle. The array is not an constant array.

Answer 1

At the lowest level, these operations mostly tend to compile to the same thing. If you're really interested, you should get your C compiler to generate assembly output (such as with gcc -S) so you can check, especially since it depends, at a bare minimum, on:

• your target platform.
• your compiler.
• your optimisation level.

You'll find that, even if there was a difference (which is doubtful), that level of micro-optimisation is mostly not worth the effort you put into it. You're better off doing macro-optimisations such as improved algorithms since that's the sort of thing that offers more return on investment.

In these sorts of situations, where the effect is likely to be minimal, I always optimise for readability.